It is known that the anti-bacterial and pharmacological properties of many naturally produced aminoglycoside antibiotics can be altered by structural modifications. For example, certain chemical modifications in the gentamicin and kanamycin family of aminoglycoside antibiotics provide structures which are less toxic than the parent antibiotic. Further, certain chemical modifications in the above family series alter the antibacterial spectrum advantageously either by increasing the intrinsic activity or increasing activity against resistant strains.
Recently, a new family of aminoglycoside antibiotics, the fortimicins, have been identified. See U.S. Pat. Nos. 3,976,768 and 3,931,400 which disclose the naturally produced parent antibiotics, Fortimicin A and Fortimicin B. Historically, once an aminoglycoside antibiotic has been in clinical use for awhile, resistant microorganisms arise. In many cases, the resistance is R-factor mediated and is attributed to the ability of the bacteria to enzymatically modify the amino or hydroxyl groups of the aminoglycoside antibiotic. It is known that in the naturally occuring fortimicin aminoglycoside antibiotics blocking the 2-hydroxy group inactivates the antibiotics.
The present invention provides 2-deoxyfortimicin antibiotics and derivatives thereof which have equal in vitro antibacterial activity when compared to the parent fortimicins. The preferred compounds of this invention have equal or increased in vivo activity. In addition, the 2-deoxyfortimicins of this invention cannot be inactivated by R-factor carrying microorganisms which can modify the 2-hydroxyl group of the parent fortimicins.